<?php
	//将timestamp,nonce,token按字典排序
		$timestamp = $_GET['timestamp'];
		$nonce = $_GET['nonce'];
		$token ='weixin';
		$signature= $_GET['signature'];
		$array =array($timestamp,$nonce,$token);
		sort($array);
	//将排序后的三个参数用sha1加密
	 	$tmpstr=implode('',$array);//join
	 	$tmpstr=sha1($tmpstr);	
	//将加密后的字符串与signature进行对比,判断该请求是否来自微信
		if($tmpstr==$signature){
			echo $_GET['echostr'];
			exit;
		}
?>